Ceramic-based stealth coating

Abstract

The utility model belongs to the technical field of electromagnetic shielding and electromagnetic stealth, and particularly relates to a ceramic-based stealth coating. The antenna is composed of the metal resonance unit and the ceramic-based medium, and the frequency selection characteristic of the pattern structure is changed by adjusting the size of the metal resonance unit, so that electromagnetic waves of corresponding frequency points can be incident to the absorption structure, and the incident electromagnetic waves are divided into two parts, one part excites induced current on the top metal frequency selective surface layer to convert electromagnetic waves into heat energy to be dissipated, the other part enters the structure, is reflected for multiple times through the reflecting surface and is subjected to interference cancellation with subsequent incident electromagnetic waves, and finally, two electromagnetic absorption mechanisms are used to realize the effect that the thickness is far smaller than the L-band wavelength. And absorbing the electromagnetic waves of the fixed frequency point of the frequency band.

Description

Technical Field

[0001] The utility model belongs to the technical field of electromagnetic shielding and electromagnetic stealth, and specifically relates to a ceramic-based stealth coating. Background Art

[0002] Electromagnetic stealth uses electromagnetic absorbing structures or materials to absorb external detection radar waves, in order to reduce the radar cross-section characteristics of the units using the unit, making each unit low detectable, thereby achieving stealth in the radar frequency band.

[0003] In recent years, with the continuous upgrading and improvement of the detection functions of reconnaissance and electronic countermeasure systems, the user units need to achieve 360° all-round stealth in order to deal with the opponent's radar detection. However, in some special locations, such as the observation windows of motor vehicles and the engine exhaust ducts of aircraft, the use of traditional absorbing materials cannot meet the use requirements, resulting in the radar scattering cross-section characteristics of these locations cannot be effectively suppressed, thus leaving safety hazards for the user units of their own side.

[0004] There are already absorbing materials with high temperature resistance, such as the material proposed by Ma et al. in Microwave dielectric properties of Al-doped ZnO powders synthesized by coprecipitation method. However, the thickness of high temperature resistant absorbing materials is often greater than 1 / 15 of their working wavelength. In particular, for high temperature resistant absorbing materials working in the L-band and S-band, the thickness is at least 1 / 10 of the working wavelength, which makes it difficult for such absorbing materials to meet some special application scenarios.

[0005] Therefore, there is an urgent need to solve the problem that existing high-temperature resistant absorbing materials working in the L and S frequency bands are too thick and difficult to meet application scenarios.

[0006] In view of this, the present utility model is proposed. Utility Model Content

[0007] The purpose of the utility model is to overcome the shortcomings of the prior art and provide a ceramic-based stealth coating.

[0008] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0009] A ceramic-based stealth coating comprises a ceramic-based dielectric layer and a metal frequency selective surface layer (FSS) stacked in sequence on a metal substrate;

[0010] The metal frequency selective surface layer includes a plurality of periodic structures which are arranged periodically and are close to each other, each periodic structure is composed of four periodic modules, and each periodic module includes a plurality of evenly arranged cylindrical metal resonance units.

[0011] Specifically, the periodic structure includes a first periodic module, a second periodic module vertically symmetrical to the first periodic module, a third periodic module horizontally symmetrical to the first periodic module, and a fourth periodic module centrally symmetrical to the first periodic module.

[0012] Specifically, the first periodic module is a square structure.

[0013] Specifically, the periodic module includes a first pattern structure formed by evenly distributed first cylindrical metal resonance units, a second pattern structure formed by evenly distributed second cylindrical metal resonance units, a third pattern structure formed by a third cylindrical metal resonance unit and a fourth cylindrical metal resonance unit respectively being centrally symmetrical, and the third pattern structure is centrally symmetrical with a fourth pattern structure.

[0014] Specifically, the first pattern structure, the second pattern structure, the third pattern structure, and the fourth pattern structure are all square structures.

[0015] Specifically, the diameter of the first cylindrical metal resonance unit is a, the diameter of the second cylindrical metal resonance unit is b, the diameter of the third cylindrical metal resonance unit is c, and the diameter of the fourth cylindrical metal resonance unit is d, wherein a≠b≠c≠d; increasing a, b, c and d will move the corresponding operating frequency point toward low frequency, and decreasing it will move the operating frequency point toward high frequency. By adjusting the diameters of a, b, c and d of the metal frequency selective surface layer resonance unit, the frequency selection characteristics of the metal pattern can be changed to achieve frequency absorption of different targets.

[0016] Specifically, the thicknesses of the first cylindrical metal resonance unit, the second cylindrical metal resonance unit, the third cylindrical metal resonance unit, and the fourth cylindrical metal resonance unit are all the same.

[0017] Specifically, the material of the cylindrical metal resonance unit includes but is not limited to copper and aluminum.

[0018] Specifically, the thickness of the metal frequency selective surface layer is 10-50um. It should be noted that the thickness of the metal frequency selective surface layer 3 can be adaptively prepared according to actual needs. The optional thickness is 10μm, 15μm, 18μm, 25μm, 30μm, 40μm, 50μm, etc., which are not listed one by one.

[0019] Specifically, the top metal frequency selective surface layer is composed of a plurality of periodic units, each periodic unit is composed of m*n periodic structures uniformly distributed in the form of m rows and n columns, m is an integer greater than or equal to 1, and n is an integer greater than or equal to 1; the front end face of the nth periodic unit located in the 1st row is flush with the front end face of the n-1th periodic unit in the 1st row, the left end face of the mth periodic unit located in the 1st column is flush with the left end face of the m-1th periodic unit in the 1st column, and the rear end face of the nth periodic unit located in the mth row is flush with the n-1th periodic unit in the mth row. The rear end faces of the units are flush, the right end face of the m-th periodic unit located in the n-th column is flush with the right end face of the m-1-th periodic unit in the n-th column; the symmetry lines of the n-th periodic unit in the same row along the left-right direction are located in the same straight line, the symmetry lines of the m-th periodic unit in the same column along the front-back direction are located in the same straight line, the right end face of the periodic unit located in the j-th row and k-th column is fit and connected with the left end face of the periodic unit located in the j-th row and k+1-th column; the rear end face of the periodic unit located in the d-th row and p-th column is fit and connected with the front end face of the periodic unit located in the d+1-th row and p-th column.

[0020] Each periodic structure is composed of 4*4 small squares with a side length of g, which are square 1, square 2, square 3, square 4, square 5, square 6, square 7, square 8, square 9, square 10, square 11, square 12, square 13, square 14, square 15 and square 16 from left to right and from top to bottom. Among them, the same pattern structure is set in square 1, square 4, square 13 and square 16; the same pattern structure is set in square 6, square 7, square 10 and square 11; the same pattern structure is set in square 2, square 5, square 12 and square 15, and the same pattern structure is set in square 3, square 8, square 9 and square 14; the pattern structure includes a first pattern structure, a second pattern structure, a third pattern structure and a fourth pattern structure with different shapes.

[0021] Compared with the prior art, the technical solution provided by the utility model includes the following beneficial effects:

[0022] The utility model is composed of a metal resonance unit and a ceramic-based medium. The frequency selection characteristics of the pattern structure are changed by adjusting the size of the metal resonance unit, so that the electromagnetic waves at the corresponding frequency point can be incident on the absorption structure. The incident electromagnetic waves are divided into two parts. One part excites the induced current in the top metal frequency selection surface layer, so that the electromagnetic waves are converted into heat energy dissipation, and the other part is incident into the structure, and is reflected multiple times by the reflection surface, and interferes with the subsequent incident electromagnetic waves. Finally, two electromagnetic absorption mechanisms are used to achieve the absorption of electromagnetic waves at a fixed frequency point in the L-band under the condition that the thickness is much smaller than the wavelength of the L-band. In addition, because the medium of the absorbing structure adopts a ceramic-based medium and a metal resonance unit, the structure can effectively cope with the electromagnetic shielding requirements in a high-temperature working environment, which greatly expands the application scenarios of absorbing materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings herein are incorporated into and constitute a part of this specification, and together with the description, are used to explain the principles of the present utility model.

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the utility model or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0025] Figure 1 It is a top view of the utility model;

[0026] Figure 2 It is a side view of the utility model;

[0027] Figure 3 This is a graph showing the reflectivity results of Example 1, Example 2 and Example 3 of the present utility model.

[0028] Among them: 1 is a metal substrate; 2 is a ceramic-based dielectric layer; 3 is a metal frequency selective surface layer; 31 is a first cylindrical metal resonance unit; 32 is a second cylindrical metal resonance unit; 33 is a third cylindrical metal resonance unit, and 34 is a fourth cylindrical metal resonance unit. DETAILED DESCRIPTION

[0029] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the accompanying drawings. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present utility model. Instead, they are only examples consistent with some aspects of the present utility model as detailed in the attached claims.

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0031] See also Figure 1-2 As shown, the utility model uses a ceramic-based stealth coating, including a ceramic-based dielectric layer 2 and a metal frequency selective surface layer 3 stacked in sequence on a metal substrate 1;

[0032] The metal frequency selective surface layer 3 includes a plurality of periodic structures which are arranged periodically and are adjacent to each other, each periodic structure is composed of four periodic modules, and each periodic module includes a plurality of evenly arranged cylindrical metal resonance units.

[0033] Specifically, the periodic structure includes a first periodic module, a second periodic module vertically symmetrical to the first periodic module, a third periodic module horizontally symmetrical to the first periodic module, and a fourth periodic module centrally symmetrical to the first periodic module.

[0034] Specifically, the first periodic module is a square structure.

[0035] Specifically, the periodic module includes a first pattern structure formed by evenly distributed first cylindrical metal resonance units 31, a second pattern structure formed by evenly distributed second cylindrical metal resonance units 32, and a third pattern structure formed by third cylindrical metal resonance units 33 and fourth cylindrical metal resonance units 34 respectively and symmetrically, and the third pattern structure is symmetrically provided with a fourth pattern structure.

[0036] Specifically, the first pattern structure, the second pattern structure, the third pattern structure, and the fourth pattern structure are all square structures.

[0037] Specifically, the diameter of the first cylindrical metal resonance unit 31 is a, the diameter of the second cylindrical metal resonance unit 32 is b, the diameter of the third cylindrical metal resonance unit 33 is c, and the diameter of the fourth cylindrical metal resonance unit 34 is d, wherein a≠b≠c≠d.

[0038] Specifically, the thicknesses of the first cylindrical metal resonant unit 31 , the second cylindrical metal resonant unit 32 , the third cylindrical metal resonant unit 33 , and the fourth cylindrical metal resonant unit 34 are all the same.

[0039] Specifically, the material of the cylindrical metal resonance unit includes but is not limited to copper and aluminum.

[0040] Specifically, the thickness of the metal frequency selective surface layer 3 is in the range of 10-50 μm; it should be noted that the thickness of the metal frequency selective surface layer 3 can be adaptively prepared according to actual needs, and the optional thickness is 10 μm, 15 μm, 18 μm, 25 μm, 30 μm, 40 μm, 50 μm, etc., which are not listed one by one.

[0041] In the following embodiments, the side length of the square structure is g, the thickness of the metal frequency selective surface layer is h1, the thickness of the ceramic-based dielectric layer 2 is h2, and a material with a dielectric constant of e1 and a dielectric loss constant of e2 is used. The dielectric constant e1 and the dielectric loss constant e2 respectively affect the changes in the absorbing frequency point and the absorbing amplitude of the structure.

[0042] Example 1

[0043] See also Figure 1-2 As shown, this embodiment provides a ceramic-based stealth coating, which includes a ceramic-based dielectric layer 2 and a metal frequency selective surface layer 3 stacked in sequence on a metal substrate 1.

[0044] The specific values ​​of the parameters in Example 1 are shown in the following table

[0045] a b c d h1 h2 e1 e2 g 9.9mm 7.3mm 20mm 15mm 0.018mm 1.6mm 10 0.02 80mm

[0046] For the curve of reflectivity of vertically incident electromagnetic waves as a function of frequency, see Figure 3 As shown, the reflection coefficients of Example 1 at 1.23GHz, 1.67GHz, 2.32GHz and 3.12GHz are -3.09dB, -3.04dB, -3.84dB and -3.85dB respectively; when the electromagnetic wave is incident on the surface of the structure, an induced current is generated in the four cylindrical metal resonant units of different sizes, and the induced current caused by the electromagnetic wave in the corresponding working frequency band is very strong. Most of the energy is converted into heat and dissipated on the surface of the resonant unit. In addition, a small part of the electromagnetic wave is continuously reflected inside the medium through the FSS surface until it interferes with the incident wave in an anti-phase manner and cancels out the incident wave; the thickness of the overall structure is 0.0005 times the wavelength of the lowest working frequency band and the overall structure has high temperature resistance, which can greatly adapt to some special application scenarios.

[0047] Example 2

[0048] See also Figure 1-2 As shown, this embodiment provides a ceramic-based stealth coating, which includes a ceramic-based dielectric layer 2 and a metal frequency selective surface layer 3 stacked in sequence on a metal substrate 1.

[0049] The specific values ​​of each parameter in Example 2 are shown in the following table

[0050] a b c d h1 h2 e1 e2 g 9mm 6.5mm 18mm 13mm 0.018mm 1.6mm 10 0.02 80mm

[0051] Example 2 The curve of the reflectivity of vertically incident electromagnetic waves changing with frequency is shown in FIG. Figure 3 As shown, the reflection coefficients of Example 2 at 1.41 GHz, 1.92 GHz, 2.65 GHz and 3.56 GHz are -3.32 dB, -2.26 dB, -3.45 dB and -3.57 dB respectively; when the electromagnetic wave is incident on the surface of the structure, an induced current is generated in the four metal resonance units of different sizes, and the induced current caused by the electromagnetic wave in the corresponding working frequency band is very strong. Most of the energy is converted into heat and dissipated on the surface of the resonance unit. In addition, a small part of the electromagnetic wave is continuously reflected inside the medium through the FSS surface until it interferes with the incident wave in an anti-phase manner and cancels out the incident wave; the thickness of the overall structure is 0.0007 times the wavelength of the lowest working frequency band, and the overall structure has high temperature resistance, which can greatly adapt to some special application scenarios.

[0052] Example 3

[0053] See also Figure 1-2 As shown, this embodiment provides a ceramic-based stealth coating, which includes a ceramic-based dielectric layer 2 and a metal frequency selective surface layer 3 stacked in sequence on a metal substrate 1.

[0054] The specific values ​​of each parameter in Example 3 are shown in the following table

[0055] a b c d h1 h2 e1 e2 g 8mm 6mm 15mm 12mm 0.018mm 1.6mm 10 0.02 80mm

[0056] For the curve of reflectivity of vertically incident electromagnetic waves as a function of frequency, see Figure 3 As shown, the reflection coefficients of Example 3 at 1.67 GHz, 2.08 GHz, 3.02 GHz and 3.85 GHz are -2.82 dB, -2.02 dB, -3.16 dB and -3.84 dB respectively; when the electromagnetic wave is incident on the surface of the structure, an induced current is generated in the four cylindrical metal resonant units of different sizes, and the induced current caused by the electromagnetic wave in the corresponding working frequency band is very strong, most of the energy is converted into heat and dissipated on the surface of the resonant unit, and a small part of the electromagnetic wave is continuously reflected inside the medium through the FSS surface until it interferes with the incident wave in an anti-phase manner and cancels out the incident wave; the thickness of the overall structure is 0.00089 times the wavelength of the lowest working frequency band, and the overall structure has high temperature resistance, which can greatly adapt to some special application scenarios.

[0057] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0058] It should be understood that the present invention is not limited to the above-described contents, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A ceramic-based stealth coating, characterized in that: It comprises a ceramic-based dielectric layer (2) and a metal frequency selective surface layer (3) which are sequentially stacked on a metal substrate (1); The metal frequency selective surface layer (3) comprises a plurality of periodic structures which are arranged periodically and are close to each other, each periodic structure is composed of four periodic modules, and each periodic module comprises a plurality of evenly arranged cylindrical metal resonance units.

2. The ceramic-based stealth coating according to claim 1, characterized in that: The periodic structure comprises a first periodic module, a second periodic module vertically symmetrical to the first periodic module, a third periodic module horizontally symmetrical to the first periodic module, and a fourth periodic module centrally symmetrical to the first periodic module.

3. The ceramic-based stealth coating according to claim 2, characterized in that: The first periodic module is a square structure.

4. The ceramic-based stealth coating according to claim 1, characterized in that: The periodic module comprises a first pattern structure formed by evenly distributed first cylindrical metal resonance units (31), a second pattern structure formed by evenly distributed second cylindrical metal resonance units (32), and a third pattern structure formed by a third cylindrical metal resonance unit (33) and a fourth cylindrical metal resonance unit (34) respectively and symmetrically at the center, and the third pattern structure is symmetrically provided with a fourth pattern structure.

5. The ceramic-based stealth coating according to claim 4, characterized in that: The first pattern structure, the second pattern structure, the third pattern structure and the fourth pattern structure are all square structures.

6. The ceramic-based stealth coating according to claim 4, characterized in that: The diameter of the first cylindrical metal resonance unit (31) is a, the diameter of the second cylindrical metal resonance unit (32) is b, the diameter of the third cylindrical metal resonance unit (33) is c, and the diameter of the fourth cylindrical metal resonance unit (34) is d, wherein a≠b≠c≠d.

7. The ceramic-based stealth coating according to claim 4, characterized in that: The thicknesses of the first cylindrical metal resonance unit (31), the second cylindrical metal resonance unit (32), the third cylindrical metal resonance unit (33) and the fourth cylindrical metal resonance unit (34) are all the same.

8. The ceramic-based stealth coating according to claim 1, characterized in that: The material of the cylindrical metal resonance unit includes but is not limited to copper and aluminum.

9. The ceramic-based stealth coating according to claim 1, characterized in that: The thickness of the metal frequency selective surface layer (3) is 10-50 um.

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